Field of the Invention
The present invention relates to a lithography apparatus, a lithography method, and a method of manufacturing an article.
Description of the Related Art
An exposure apparatus which transfers a mask pattern onto a substrate is one of apparatuses to be used in a manufacturing step (lithography step) of a semiconductor device or the like. In this exposure apparatus, it is necessary to accurately arrange the substrate surface on the image formation surface (focusing surface) of a projection optical system in order to accurately overlay the mask pattern on a shot region on the substrate. Japanese Patent Laid-Open No. 2001-15422 has proposed a method of correcting a positional shift of the surface of a substrate in a direction (Z direction) parallel to the optical axis of a projection optical system, which is produced by driving of a substrate stage in a direction (XY direction) perpendicular to the optical axis, in a scanning exposure apparatus which exposes the substrate while scanning it. This positional shift can occur due to, for example, the shape of the surface of a stage base on which the substrate stage moves.
In this scanning exposure apparatus, control is so performed that the substrate surface is arranged on an image plane in parallel with substrate scanning. However, if the control system has a manufacturing error of a mechanism (for example, the stage base), a measurement error of a measuring device (for example, a laser interferometer), or a control error (for example, a stationary error) of a controller, it becomes difficult to arrange the substrate surface on the image plane.